Chip Capacitor Coating Electron Microscopy Study

Multi-layer ceramic capacitors (MLCC) are important electric components which are used in almost all areas of electronics. With the expansion of the scope of application and performance requirements of its further improvement, the quality and reliability problems of capacitors become increased more and more. A considerable portion of questions were caused by the coating quality. Thus the quality of coating directly affects the reliability of electronic systems. Enhancing the quality and reliability of the coating for chip capacitor manufacturers has already become a critical question. The goal of this dissertation based on the back ground of the selected topic with the multi-layer ceramic capacitors and the organic film capacitors chip capacitors of R&D process, a series of works that affect the quality of the coating were studied by means of microscopic analysis, evaluating the quality of the coating, providing the basis for process improvement by failure analysis. The goal of this study uses SEM and its attached EDS as the main research methods for conducting an electron microscopy analysis of chip capacitors reliability and the following results are obtained:(1) The preparation method for the reliability sample analysis of MLCC was conducted by different experimental goals and various methods. Focus on destructive physical analysis (DPA) of multilayer ceramic capacitors sample preparation.(2) Aimed at the matching problem of ceramic materials for MLCC devices and terminal electrode's silver slurry, selected three kinds of slurry from various manufactories, analyzed and compared the physical properties of the three slurry, blocking effect, the quality of sintering and the performance test results of terminal electrode after plating, identify the optimal silvery slurry which is fully compatible with ceramic material, and determined its matching private slurry combining with the requirements of slurry on the process conditions.(3) The problem of resistance to soldering heat performance degradation reasons of terminal electrodes with Sn-Pb surface coating in devices was studied. The results show that during the firing processes of silver termination paste, the remains of glass phase were produced, which resulting in the discontinuous of the Sn-Pb surface coating and deterioration of the weldability of the terminal electrodes of MLCC because the glass phase was no-conductive material.(4) The devices which have the welding failure were studied with microscopes, a large number of abnormal matters were found on the surface of problem samples. Using electron microprobe analysis to do further analysis, the problem of welding failure of tin-coating in the devices which are produced by oxidation. As the high melting point of tin oxide, thermal conductivity, poor welding lead solder in the infiltration of poor welding results affect the devices.(5) The selected silver powders, dip-coating, sintering process affecting the quality of electrode was studied, and its microstructure of the electrode was investigated by SEM. The experimental results show that microstructure of the electrode exist problems and some typical defects in the terminal electrode such as the electrode permeation, the cracking, coating pore, coating bubble and silver layer defect were summarized. These phenomena indicate that the product quality reason was the defects caused by inappropriate process and play an important role in the final quality of MLCCs. The analysis outcomes are great hold-up for improving the yield and quality of devices.(6) Against the problem of lead-free pin line in film capacitors devices, utilize hot-dip process and the effects of several technical parameters on the coatings such as the dipping time, and temperature are described for determining the optimum conditions, Experiment results significantly favored the processing of pin line in film capacitors devices.Combine the analysis work with the electrode dip-coating and plating process and production practices, some practical improved methods are discussed for the problems. The technology improvement measures had been applied from the conditions of process control, products examination, quality evaluation and failure analysis. The reliability of chip capacitor products was effective promoted. The failure rate is effectively lowered and has a positive role in preventing failure.